Friends list? There's not much to it. If you devWATCH someone (there's a link in the top-right corner of every user's page) it adds them to your friends list and your message centre will update you whenever they make a new journal, poll or deviation.
Well, generally try to get involved in the community, post comments, give feedback to people, and don't forget to upload your own creations too, even if you're not an artist in the stereotypical sense, there's lots of sections for writing, both fictional and non-fictional, photography and other stuff, so yeah, that's about the best advice I can think of.